問題 L: 槍聲問題

#include <bits/stdc++.h>
#pragma
using namespace std;
int f(long long int a,long long int b){
  while(b!=0){
    int temp=a%b;
    a=b;b=temp;
  }
  return a;
}
int main() {
  long long int n,m,t,t1,t2,i,k,j,s,sum;
  scanf("%lld",&s);
  scanf("%lld",&t1);
  scanf("%lld",&t2);
  t1=t1+1;
  t2=t2+1;
  k=f(t1,t2);
  t=t1/k*t2;
  if(t1>t2)
  {
    long long int temp=t1;
    t1=t2;t2=temp;
  }
  n=(s-1)*t1;
  m=n/t;
  sum=2*s-1-m;
  printf("%d\n",sum);
  return 0;  
}